INSECT POWDER. 45 
Fromme (86) reports the ash content of insect powder as being 
between 6.5 and 9.5 per cent. In a later article (87) he criticizes 
the method of Trottner in which the number of pollen grains in 
1 milligram of powder is estimated, and the value of the 
powder thus determined, the greater the number of pollen grains 
the better the powder. Fromme determined the ash and ether 
extract, observed the color and odor of the ether extract, counted 
the number of pollen grains in 1 milligram of powder, and made 
physiological tests with flies upon 7 samples of insect powder, with 
the result that some of the most active powders were shown to con- 
tain fewer pollen grains than other powders prepared largely from 
stems. The analytical results on these 7 samples are given in Table 
23. 
Table 23. — Examination of active insect powder (Fromme). 
Ash. 
Ether 
extract. 
Color of ether extract. 
Pollen 
grains in 
lmg. 
Per cent. 
8.21 
Per cent. 
6.37 
6.00 
6.15 
5.85 
6.27 
5.01 
3.40 
Golden yellow 
308 
7.17 
2,415 
2,900 
230 
7.25 
Golden yellow 
8.00 
Greenish yellow 
8.84 
Golden yellow 
3,000 
710 
8.00 
Dirty green 
7.10 
Greenish 
294 
SUMMARY OF METHODS. 
From the foregoing review of physiological, microscopical, and 
chemical methods for determining the genuineness of commercial 
samples of insect powder, it is seen that while satisfactory chemical 
or microscopical methods have been developed for detecting the 
addition of adulterants such as other species of flowers, curcuma, 
and Pyrethrum stems, these methods are not capable of accurately 
determining quantitatively the extent of this adulteration, although 
the amount of stems can be approximated by comparing under the 
microscope the unknown mixture with known mixtures of powdered 
flowers and stems. Of course, the amount of an inorganic adul- 
terant, like lead chromate, may be accurately determined by chemical 
analysis, but such adulteration is now quite rare. Probably over 95 
per cent of the adulteration of insect powder at the present time is 
with ground Pyrethrum stems. 
One of the most promising microscopic methods for examining 
insect powder thus far proposed seems to be that of Trottner, in 
which the number of pollen grains in the weighed quantity of sample 
is estimated. This number, however, varies so in different powders 
of equal effectiveness as to prohibit a rigorous quantitative applica- 
tion of the method. 
